Search by size of object type field elastic search

Question

I have a mapping like this:

{
  "post": {
    "properties": {
      "author_gender": {
        "type": "string",
        "index": "not_analyzed",
        "omit_norms": true,
        "index_options": "docs"
      },
      "author_link": {
        "type": "string",
        "index": "no"
      },
      "content": {
        "type": "string"
      },
      "mentions": {
        "properties": {
          "id": {
            "type": "integer"
          },
          "name": {
            "type": "string"
          },
          "profile_image_url": {
            "type": "string"
          },
          "screen_name": {
            "type": "string"
          }
        }
      }
   }
}

I need to search by the size of the mentions object. I have tried this:

{
  "filter": {
    "script": {
      "script": "doc['mentions'].values.length == 2"
    }
  }
}

This is not working. Gives an error

nested: ElasticSearchIllegalArgumentException[No field found for [mentions] in mapping with types [post]];

I have also tried replacing the script part with doc['mentions.id'].value.length == 2. It is also erroring

nested: ArrayIndexOutOfBoundsException[10];

How to query records with mentions object size 2 ?

Answer 1

The elasticsearch guide recommends using size() instead of length for objects. So try this:

{
 "filter": {
   "script": {
     "script": "doc['mentions.id'].values.size() == 2"
    }
  }
}

All the best.